Gunshot injury is the leading cause of death in 10-19 year old African American males and the second leading cause of adolescent death overall. Most adolescents who are killed with guns are shot during assaults (60 percent) and for each gunshot assault that is fatal, 7 adolescents require emergency department (ED) treatment for non-fatal assaultive gunshot trauma. Additionally, each day more than 70 adolescents require ED treatment for non-fatal assaultive injuries inflicted with non-gun weapons. Nevertheless, little is known about the epidemiology of assaultive injury from guns and other weapons among adolescents. By using an epidemiological space-time modeling approach, we have developed and pilot-tested an innovative, portable technology for dynamically mapping the activities of adolescents thereby allowing very accurate estimation of their exposure to alcohol and firearms on a minute-to-minute basis. To determine gunshot injury risk, we propose conducting a population-based case-control study. Adolescents 10-19 years of age presenting to the ED of 2 inner-city Philadelphia hospitals for assault-related gunshot injuries will be compared with a randomly selected, population-based sample of control subjects 10-19 years old. As a secondary aim, adolescents presenting for non-gunshot assault injuries will be enrolled as a second case group and compared with the same sample of control subjects to determine non-gun injury risk. Each case and control subject will be interviewed using portable, computerized mapping technology to create a dynamic graphic that provides a minute-by-minute record of how, when, with whom, and where the subject spent time as he or she walked or otherwise traveled from location to location and from activity to activity on the day of the injury (cases) or 1-4 days earlier designated randomly (controls). Each subject will be asked about his or her use of alcohol and firearms that day, and about how other people around him or her used alcohol and firearms that day (e.g., people drinking alcohol on street corners; firearms kept at home). Secondary data we will link, along with the narrative data, to the map will identify additional exposure and confounding factors including characteristics of streets, buildings, and neighborhoods. Logistic regression analyses will investigate whether adolescents who consume alcohol and/or carry firearms, and/or whose daily activities occur in surroundings rich in alcohol and/or firearms, face a differential risk of being shot with a firearm or injured in a non-gun assault. This study will help to identify how adolescents are restricted in time and space by their daily activities, thereby identifying particular locations and times of enhanced, and reduced, assaultive injury risk.